Abstract Glaucoma is a chronic ocular disease that causes visual impairment and blindness. Its prevalence positions it as one of the most important etiologies underlying visual impairment worldwide.1-3 Glaucoma?s pathologic changes occur at the optic nerve head, leading to what is termed ?the hallmark defect of glaucoma,? the nerve fiber bundle defect, which is characterized clinically by visual field (VF) testing. Carefully conducted VF testing under standardized conditions provides clinicians with both a measure of the impact that glaucoma has on visual function and the effect that treatment is having on controlling glaucomatous damage. Decisions made by eye care practitioners about how best to care for their patient with glaucoma are substantially guided by the results from VF testing. When a patient is diagnosed with or being treated for glaucoma knowledge of not only the patient?s initial VF status but also the likelihood of VF progression they will experience is critical to their care. Identification of risk factors that help predict VF change over time enables more informed decisions about treatment. The patient needs to understand these factors as well, since their adherence to commonly prescribed medical treatment and their ability to cope with the condition is affected by how well they understand glaucoma and its effect on their vision. Among the many studies that have attempted to characterize VF progression over time due to open- angle glaucoma (OAG), the most prevalent type of glaucoma in the United States, two large clinical trials supported by the National Eye Institute (NEI) embrace the spectrum of OAG severity, employed the same, well-standardized VF testing approach, and collected data over an extended period of follow-up ? the Advanced Glaucoma Intervention Study (AGIS) and the Collaborative Initial Glaucoma Treatment Study (CIGTS). The overarching aim of the proposed research in this grant application is to make use of the wealth of information gathered in these two longitudinal studies to increase our understanding of VF progression over time across the spectrum of glaucoma severity, to evaluate patterns of loss over time, and to identify factors that enable us to better predict VF progression. These aims depend on analyses that use data collected from long-term follow-up of almost 1200 patients with OAG who participated in the AGIS and CIGTS clinical trials. The proposed research relates closely with gaps in our knowledge identified in a report issued by the NEI,4 in which the glaucoma panel noted this need: ?improved statistical methods are required for determining progression.? This identified gap in knowledge relates directly to the importance of statistical modeling to identify factors that predict VF progression, and the still applicable conclusion that a VF expert stated in 2007: ?currently, there is no consensus on a quantitative method to evaluate glaucomatous progression for either structure or function.?5